Battery fault diagnosis system based on gmr magnetic sensor, manufacturing method and battery fault diagnosis method

Abstract

The application discloses a battery fault diagnosis system based on a GMR magnetic sensor, a manufacturing method and a battery fault diagnosis method, and comprises a GMR magnetic sensor, a magnetic force line concentrator, a data acquisition system and a scanning platform, wherein the GMR magnetic sensor is arranged on a substrate and is used for detecting magnetic field changes generated in the working process of a battery and outputting an electric signal; the magnetic force line concentrator is arranged on both sides of the GMR magnetic sensor and is used for concentrating external magnetic fields to the sensitive area of the GMR magnetic sensor; the data acquisition system is connected with the GMR magnetic sensor and is used for collecting, amplifying and processing the electric signal; and the scanning platform is used for driving the GMR magnetic sensor to move relative to the measured battery so as to obtain magnetic field data of different positions of the battery. The application effectively solves the problems of insufficient integration precision and low magnetic field capturing efficiency of the traditional GMR sensor.

Description

Technical Field

[0001] This invention relates to the field of battery monitoring technology, and in particular to a battery fault diagnosis system, manufacturing method, and battery fault diagnosis method based on a GMR magnetic sensor. Background Technology

[0002] With the rapid development of electric vehicles and energy storage systems globally, the safety issues of lithium-ion batteries are becoming increasingly prominent. In 2024, my country's lithium battery production reached 1170 GWh, with an industry output value exceeding 1.2 trillion yuan. However, from January to October 2024, 2105 electric vehicle fires occurred in my country. Lithium-ion battery failures not only threaten system operational safety but also directly impact the healthy development of the entire industry chain. During long-term use, due to manufacturing differences, aging, thermal runaway, internal micro-short circuits, and other faults, batteries may experience inconsistent capacity between individual cells, unbalanced current distribution, or even thermal propagation accidents.

[0003] Traditional battery monitoring technologies have many limitations. Currently, the mainstream approach assesses battery status by measuring parameters such as current and voltage during charging and discharging. While current and voltage sensing technologies are mature in current commercial lithium-ion battery packs—for example, in existing BMS (Battery Management Systems)—dedicated integrated circuits (ICs) are typically used to measure the voltage of cells connected in series. The total voltage of the battery pack is obtained by summing the voltages of each cell. However, this approach cannot detect changes in the electrode potential within the cells, primarily focusing on external parameter monitoring at the module or pack level. Voltage and current are essentially lagging and indirect reflections of the battery's internal state, rather than real-time, direct measurements. Other methods, such as Kalman filtering and equivalent circuit models, rely on accurate battery models to extrapolate the battery's internal state. This extrapolation process itself takes time and depends on potentially outdated models and parameters, making it difficult for their response speed to keep pace with the actual physicochemical changes within the battery.

[0004] Other solutions, such as temperature-based battery monitoring, suffer from lag because early internal short circuits do not cause significant changes in battery surface temperature, and the internal temperature cannot be directly measured. Currently, thermal imbalances in large commercial battery packs mostly originate from cell non-uniformity, which temperature monitoring cannot detect in a timely manner. Furthermore, sound-based detection is susceptible to environmental noise interference; gas composition-based monitoring is only suitable for thermal runaway early warning; optical image detection equipment has low penetration depth and high cost; and detection methods based on nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) face problems such as large equipment size, high cost, and slow scanning speed, making it difficult to capture rapid dynamic processes inside lithium batteries in real time. Magnetoelectric (ME) sensors for magnetic field imaging are complex and costly; flux-gate scanning measurements, while reflecting capacity consistency, rely on mechanical scanning and cannot achieve real-time continuous monitoring. Moreover, most of these methods require contact measurement, making real-time measurement impossible during normal battery operation and hindering large-scale integration.

[0005] In contrast, magnetic field detection-based sensor technology has become an important means of current monitoring. Compared with traditional voltage and current measurements, the response of magnetic field signals to changes inside the battery is almost instantaneous, unaffected by significant hysteresis effects such as electrochemical polarization. This provides a reliable foundation for achieving true real-time monitoring, especially for early warning of faults such as internal micro-short circuits. Currently, Hall sensors, anisotropic magnetoresistive (AMR), tunneling magnetoresistive (TMR), and fluxgate sensors are mainly used for non-contact measurements. Hall sensors are highly scalable, have good linearity, and simple structure, making them suitable for low magnetic field measurements; however, they exhibit significant temperature drift, requiring additional temperature compensation, and their high power consumption and large size limit miniaturization applications. AMRs are characterized by high sensitivity and low cost, making them suitable for detecting weak magnetic field changes; however, their output signals exhibit nonlinear characteristics, the calibration process is complex, and their sensitivity and linear response are poor under low magnetic field conditions. TMR (Transient Magnetic Range) sensors excel in sensitivity, response frequency, and signal-to-noise ratio, enabling ultra-high precision current measurement. However, their manufacturing process requires ultra-vacuum coating equipment, resulting in high costs. They are also prone to performance degradation at high temperatures and rely on dedicated ASICs, hindering their widespread adoption in low-cost systems. Fluxgate sensors, on the other hand, stand out in terms of accuracy, hysteresis-free characteristics, temperature stability, response speed, and practical application maturity. However, their manufacturing process is complex and costly, and they are susceptible to interference from environmental magnetic fields, resulting in insufficient flexibility in certain scenarios.

[0006] Therefore, those skilled in the art are dedicated to developing a current detection and diagnostic technology to solve the problems of insufficient real-time performance, limited monitoring accuracy, and high integration difficulty in current traditional battery monitoring methods. Summary of the Invention

[0007] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to solve the problems of insufficient real-time performance, limited monitoring accuracy and high integration difficulty in the current traditional battery monitoring methods.

[0008] To achieve the above objectives, this invention provides a battery fault diagnosis system based on a GMR (Giant Magnetoresistance) magnetic sensor, characterized in that it includes: GMR magnetic sensors, magnetic field line concentrators, data acquisition systems, and scanning platforms. in: The GMR magnetic sensor is disposed on the substrate and is used to detect changes in the magnetic field generated during battery operation and output an electrical signal. The magnetic field line concentrator is disposed on both sides of the GMR magnetic sensor and is used to concentrate the external magnetic field to the sensitive area of ​​the GMR magnetic sensor. The data acquisition system is connected to the GMR magnetic sensor and is used to acquire, amplify, and process the electrical signal; The scanning platform is used to move the GMR magnetic sensor relative to the battery under test in order to obtain magnetic field data at different locations of the battery.

[0009] This invention employs magnetoresistive effect technology, which can be miniaturized to the millimeter level, making it easy to directly embed inside the battery cell or closely adhere to the battery surface, thereby realizing a high-density monitoring network at the cell level within the battery pack and providing more refined data support for battery health status assessment.

[0010] This invention employs a magnetic multilayer film manufacturing process to achieve an integrated structure of GMR magnetic sensor and magnetizer, enabling precise position control. It utilizes a structural design combining GMR magnetoresistive effect with magnetizer, allowing external magnetic fields to be effectively focused onto the GMR sensitive area, achieving an accuracy of nT or even higher. The GMR magnetic sensor used exhibits excellent uniformity and maintains stable output without complex calibration.

[0011] This invention effectively solves the problems of insufficient integration accuracy and low magnetic field capture efficiency of traditional GMR sensors. The structural design of the magnetizer significantly improves the detection resolution of weak magnetic field changes, enhances the ability to resist environmental noise interference, improves detection stability and long-term reliability, and promotes the practical application of GMR magnetic sensors in the field of high-precision battery monitoring. The uniformity ensures the reliability and comparability of data from various sensors in the monitoring network, reduces the difficulty of system integration and maintenance costs, and provides high consistency and high reliability technical support for high-density battery pack monitoring.

[0012] Furthermore, the GMR magnetic sensor includes a substrate, GMR lines disposed on the substrate, and magnetic field line concentrators disposed on both sides of the GMR lines, wherein the GMR lines have a tortuous structure.

[0013] Furthermore, the magnetic field line concentrator is a magnetic thin film structure, and its magnetization direction is perpendicular to the GMR lines.

[0014] Furthermore, a protective film is provided on the surface of the GMR magnetic sensor.

[0015] Furthermore, the scanning platform includes slide rails arranged perpendicularly to each other and a stepper motor connected to the slide rails.

[0016] Furthermore, the data acquisition system includes a signal amplification circuit, an analog-to-digital conversion module, and a data storage unit.

[0017] On the other hand, the present invention provides a battery fault diagnosis method based on the GMR magnetic sensor, characterized by comprising the following steps: Provide an excitation signal to the GMR magnetic sensor to bring it into working condition; The GMR magnetic sensor is used to detect changes in the magnetic field generated during battery operation and outputs an electrical signal. The scanning platform moves the GMR magnetic sensor relative to the battery to collect magnetic field data at different locations on the battery. The collected magnetic field data is processed to obtain information on the distribution of the battery's magnetic field. The battery status is analyzed based on the magnetic field distribution information to achieve fault diagnosis.

[0018] This invention divides the battery area within the measurement plane into multiple sub-regions longitudinally, and an electric linear displacement platform scans along a scanning path according to preset motion parameters. The scanning platform consists of two mutually perpendicular slide rails, each equipped with a stepper motor. A stepper motor controller precisely drives the motors, moving the battery along the preset path.

[0019] The present invention provides a platform that can achieve precise linear displacement, improving the accuracy of magnetic field data acquisition. It drives the GMR magnetic sensor to move mechanically in space with a step size of 1 cm, scans lithium-ion battery cells along a Z-shaped path, and realizes the measurement of the magnetic field distribution on the battery surface, providing reliable data support for subsequent magnetic field distribution characteristic analysis.

[0020] Furthermore, the battery measurement area is divided into multiple sub-regions and scanned according to a preset path.

[0021] Furthermore, the scanning path is a Z-shaped path.

[0022] Furthermore, the electrical signal is processed by a lock-in amplifier to suppress background noise.

[0023] On the other hand, the present invention provides a method for manufacturing the battery fault diagnosis system, characterized in that it includes: GMR line patterning is performed on the substrate surface; Magnetic field line concentrator patterning is performed on the substrate surface; Electrode patterning is performed on the substrate surface, and an electrode layer is fabricated. A protective film is prepared on the substrate surface, and the electrode area is etched to expose the electrode.

[0024] Furthermore, the GMR lines are prepared by ion beam etching, the magnetic field line aggregator is prepared by sputtering and patterned by lift-off process, and the protective film is prepared by PECVD process.

[0025] Technical effect

[0026] GMR magnetic sensors, based on the giant magnetoresistance effect, achieve high-precision detection of magnetic fields by observing the significant change in resistivity of a multilayer magnetic film under the influence of an external magnetic field. They possess characteristics such as high sensitivity, excellent thermal stability, a wide detection range, non-contact detection, and resistance to environmental interference. They can directly and rapidly acquire the weak magnetic field changes generated by electrochemical reactions within the battery. This non-contact detection method avoids physical interference with the battery, enabling real-time and continuous monitoring and providing direct and accurate signals for battery health assessment. More importantly, the miniaturization of GMR technology allows for easy integration into battery management systems, enabling high-density monitoring of individual cells and even battery packs, providing an efficient and reliable solution for battery safety early warning and fault diagnosis.

[0027] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a GMR magnetic sensor according to a preferred embodiment of the present invention; Figure 2 This is a ground-side view of a GMR magnetic sensor according to a preferred embodiment of the present invention; Figure 3 This is a framework diagram of a battery fault diagnosis method according to a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of battery detection according to a preferred embodiment of the present invention. Detailed Implementation

[0029] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0030] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0031] like Figure 1-2 As shown, the substrate includes a plate-shaped substrate 5 (GMR wafer). A GMR line 1 is formed on the upper surface of the substrate 5. A first magnetic field concentrator 2a and a second magnetic field concentrator 2b are respectively positioned on either side of the GMR line 1 on the upper surface of the substrate 5, with the magnetization direction between the two magnetic field concentrators perpendicular to the GMR line 1. An electrode is covered at the tail of the GMR line 1, and the two electrodes are electrically connected to a first electrode pin 4a and a second electrode pin 4b, respectively. A SiO2 protective film 3 is formed on the upper surface of the substrate 5, the upper surface of the GMR line 1, and the upper surface of the magnetic field concentrators. The GMR line 1 has a zigzag structure, with a linewidth of 5µm, a length of 500µm, and a gap of 15µm. The magnetic field concentrators are rectangular FeNi thin films with a thickness of 2µm. The bottom electrode layer is a Cr / Cu electrode layer with a thickness of 10nm / 150nm. The SiO2 protective film 3 has a thickness of 20nm.

[0032] GMR line 1 has a zigzag structure, with a line width of 5µm, a length of 500µm, and a gap of 15µm.

[0033] The magnetic field line concentrator is a rectangular FeNi thin film with a thickness of 2µm.

[0034] The bottom electrode layer is a Cr / Cu electrode layer with a thickness of 10nm / 150nm.

[0035] The upper layer of the electrode is an Au electrode layer with a thickness of 150 nm.

[0036] The thickness of the SiO2 protective film 3 is 20 nm.

[0037] This embodiment also includes a method for fabricating a highly sensitive GMR magnetic chip based on a magnetic field line aggregator, comprising the following steps: Step 1: Patterning GMR line 1. GMR line 1 is patterned on the surface of substrate 5. Step 2: Fabrication of the magnetic field line gatherer, patterning the magnetic field lines on the surface of substrate 5; Step 3: Electrode substrate fabrication. Electrode patterning is performed on substrate 5, and then a Cr / Cu electrode layer is deposited. Step 4: Fabrication of SiO2 protective film 3. SiO2 protective film 3 is processed on the entire surface of substrate 5. Then, electrode patterning is performed, and the SiO2 layer on the electrode surface is etched until the electrode is exposed. GMR lines 1 were fabricated using an ion beam etching process.

[0038] The magnetic field line aggregator was fabricated by sputtering and patterned using a liftoff process.

[0039] The electrodes are fabricated using a sputtering process.

[0040] The SiO2 protective film 3 was fabricated using the PECVD process.

[0041] like Figure 3-4 As shown, this embodiment also includes a battery monitoring method based on a highly sensitive GMR magnetic chip using a magnetic field line concentrator: This solution includes a GMR magnetic sensor, the battery under test, a digital source meter 2450, and a data acquisition system. The GMR sensor used in this invention is a uniaxial magnetic field sensor, requiring the measurement direction to be specified. Considering the battery structure and the characteristics of the induced magnetic field distribution, the magnetic field component in the x-axis direction changes more significantly and exhibits stronger regularity. Therefore, this invention selects the magnetic field component in the x-axis direction on the lithium battery surface as the object of analysis.

[0042] A regulated DC power supply outputs a 20V excitation signal, which is used to drive the excitation coil of the GMR magnetic sensor, enabling the sensor to enter the working state.

[0043] GMR magnetic sensors are used to detect subtle changes in the magnetic field generated during battery operation, enabling non-contact battery status monitoring. A single sensor is less than 10mm × 5mm × 2mm in size; it offers nT-level detection accuracy and consumes less than 100mW of power. It can be directly embedded inside a battery cell, closely attached to the battery surface, or maintained at a distance of 0.5-2mm from the battery cell. GMR magnetic sensors convert changes in the internal magnetic field of the battery into electrical signals.

[0044] The magnetic field data is acquired using scanning sampling. Considering the sensor size and the magnetic field distribution characteristics of the battery surface, the battery area within the measurement plane is uniformly divided longitudinally into multiple sub-regions. An electric linear displacement platform measures the magnetic field data according to preset motion parameters along the scanning path. This platform achieves precise linear displacement, improving the accuracy of magnetic field data acquisition and providing reliable data support for subsequent magnetic field distribution characteristic analysis. The scanning platform consists of two mutually perpendicular slide rails equipped with stepper motors. A stepper motor controller precisely drives the motors, moving the GMR magnetic sensor mechanically in space in 1cm steps along the preset scanning path, scanning the lithium-ion battery cells along a Z-shaped path to measure the magnetic field distribution on the battery surface. Test data is acquired through a data acquisition system, which mainly includes signal amplification circuits, an A / D conversion module, and data storage units (such as FLASH media).

[0045] The specific workflow is as follows: (1) The sensor is connected to the excitation signal output by a regulated DC power supply; (2) Calibrate the linearity of the sensor using a standard magnetic field source (100nT, 10Hz) and record the output signal; (3) Set up a data acquisition system with a sampling rate of 10kHz and use bandpass filtering to avoid power frequency interference.

[0046] (4) The sensor detects the change in magnetic field and outputs a signal that is proportional to the magnetic field strength generated by the battery being tested.

[0047] (5) The linear platform moves the GMR magnetic sensor to scan the battery and collect magnetic field data.

[0048] (6) The lock-in amplifier extracts the sensor signal and suppresses background noise, so that the magnetic field can be accurately measured and the monitoring results can be transmitted to the battery management system.

[0049] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A battery fault diagnosis system based on a GMR magnetic sensor, characterized in that, include: GMR magnetic sensors, magnetic field line concentrators, data acquisition systems, and scanning platforms. in: The GMR magnetic sensor is disposed on the substrate and is used to detect changes in the magnetic field generated during battery operation and output an electrical signal. The magnetic field line concentrator is disposed on both sides of the GMR magnetic sensor and is used to concentrate the external magnetic field to the sensitive area of ​​the GMR magnetic sensor. The data acquisition system is connected to the GMR magnetic sensor and is used to acquire, amplify, and process the electrical signal; The scanning platform is used to move the GMR magnetic sensor relative to the battery under test in order to obtain magnetic field data at different locations of the battery.

2. The battery fault diagnosis system based on GMR magnetic sensors as described in claim 1, characterized in that, The GMR magnetic sensor includes a substrate, GMR lines disposed on the substrate, and magnetic field line concentrators disposed on both sides of the GMR lines, wherein the GMR lines have a tortuous structure.

3. The battery fault diagnosis system based on GMR magnetic sensors as described in claim 1, characterized in that, The magnetic field line concentrator is a magnetic thin film structure, and its magnetization direction is perpendicular to the GMR lines.

4. The battery fault diagnosis system based on GMR magnetic sensors as described in claim 1, characterized in that, The scanning platform includes slide rails arranged perpendicularly to each other and stepper motors connected to the slide rails.

5. The battery fault diagnosis system based on GMR magnetic sensors as described in claim 1, characterized in that, The data acquisition system includes a signal amplification circuit, an analog-to-digital conversion module, and a data storage unit.

6. A battery fault diagnosis method based on a GMR magnetic sensor according to any one of claims 1-5, characterized in that, Includes the following steps: Provide an excitation signal to the GMR magnetic sensor to bring it into working condition; The GMR magnetic sensor is used to detect changes in the magnetic field generated during battery operation and outputs an electrical signal. The scanning platform moves the GMR magnetic sensor relative to the battery to collect magnetic field data at different locations on the battery. The collected magnetic field data is processed to obtain information on the distribution of the battery's magnetic field. The battery status is analyzed based on the magnetic field distribution information to achieve fault diagnosis.

7. The battery fault diagnosis method based on GMR magnetic sensors as described in claim 6, characterized in that, The battery measurement area is divided into multiple sub-regions and scanned according to a preset path.

8. The battery fault diagnosis method based on GMR magnetic sensors as described in claim 6, characterized in that, The scanning path is a Z-shaped path.

9. A method for manufacturing a battery fault diagnosis system according to any one of claims 1-5, characterized in that, include: GMR line patterning is performed on the substrate surface; Magnetic field line concentrator patterning is performed on the substrate surface; Electrode patterning is performed on the substrate surface, and an electrode layer is fabricated. A protective film is prepared on the substrate surface, and the electrode area is etched to expose the electrode.

10. The manufacturing method as described in claim 9, characterized in that, The GMR lines are prepared by ion beam etching, the magnetic field line aggregator is prepared by sputtering and patterned by lift-off process, and the protective film is prepared by PECVD process.

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